Bill Kielb
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Posts posted by Bill Kielb
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5 hours ago, Kelly in AK said:
Some people glaze greenware, it works
FYI - Quite often once fire folks will do a single firing at bisque speeds. In effect a bisque first to burnout everything then continue on to glaze temp, usually for tested clay and glaze products that work well this way without excessive glaze defects. If their clay is known clean or tested with a glaze known to work without issue then not so much at the reduced speed but the tested speed. I would not ignore the time at temperature unless verified ok through prior testing.
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1353 is cone 017 ish. I assume you were trying to go to cone 04. I would suggest refine to 04, hopefully you are using cones. Bisque firing removes organics and chemically combined water so how much time and how much time at temperature is the important part. I would troubleshoot the kiln, fix it then re-bisque to desired cone.
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Good find! They appear to be out of stock though. But now we know the measurements!
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They are still in business so a call to Amaco might be revealing. They also seem to sell Amaco motors as well as brushes on their site. Maybe matchup to what you have. Your motor hopefully has a nameplate. Amaco website https://shop.amaco.com/equipment/parts/brent/wheel-motors/
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I use a regular banding wheel often when I spray, most often cover it prior with cardboard or often with a small plastic bag over just the head and then set a piece of cardboard. It’s never motorized though, I need to hand spin it for control while hand spraying. I use my medium height banding wheel often. Whatever your final cover is it needs to be absorbent with minimal puddling and stiff enough to resist the air from the sprayer. When I am lazy I’ll just take a low height banding wheel and neatly cover and tuck in newspaper. All result in hand control (which I need) and minimal cleanup at the end of the day.
With this setup I hand spray with regular HVLP spray gun (glaze), touch up gun (glaze) and even airbrush (underglaze)
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Yes, mostly ought to be fine. One color can influence another a bit I suppose on occasion but folks use liner glazes different than their exterior glaze all the time. Folks often dip their tiles … 3 second, 5 second dip …. 1 coat, 2 coats. So using test tiles and brush applying each side has its drawbacks.
With respect to glazing the outside and not the inside or Vice versa this can create an unbalanced stress in the clay as the glaze often squeezes the clay so to speak. This tiny bit of compression can increase the strength of the ware significantly. So one side glazed and the other not can cause unequal stress in the ware. End result - more fragile ware occasionally breaking suddenly when someone puts hot coffee in a cold mug for instance. Fully glazed well matched - glaze and clay- generally enhances the durability of the ware.
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3 hours ago, MLSrunner said:
have been searching my house endlessly ( 4 years now) looking for mold as I have high levels of both Ochratoxin A and Mycophenolic Acid. Our entire house has been torn up. My office is empty right now and we have torn out a wall to look inside....... and yet no sign of mold or water damage. I have been banging my head against the "literal" wall trying to figure this out and then it suddenly occurred to me that I have an issue in my office and in my bedroom. Both of those rooms have clay on the walls!!!! I have the HLA gene, the MTHFR gene and even the last gene that makes me one of the most sensitive to mold. It is a real thing.
These seem to be very specific compounds / derivations of mold. Have you considered real mold testing and counts and characterization of mold present in your environment along with indoor air quality measurements. It might quantify and explain this as well as your doctors and hygienist may be able to suggest air filtration as a staple for you regardless of the origination. Most mold originates in the outside environment and then just finds ideal conditions for growth. Testing could reveal your area and environment are conducive to its growth providing some path to minimizing your exposure. Medical grade hepa very likely traps 99% of the spores so this could possibly be something that would help clay or no clay. Mycotoxins may be too small to filter but filtering mold could reduce the potential of specific molds that produce mycotoxins.
Anyway, this seems that real certified testing could help point you in a clearer direction than just searching for an origin. Understanding the origin (likely outdoors) and ways to modify your indoor environment (humidity, temperature, filtration) maybe could provide a path to reduction. Understanding if your current outdoor environment is high in these spore counts may also provide another strategy towards minimizing infiltration. My opinion, real air born testing inside and outside your home by a certified hygienist and real lab analysis could provide quantifiable help with your situation.
I would measure first and foremost before demolition. Demolishing things can lead to spreading mold around. Most mold remediation is done carefully so as not to spread, then everything is cleaned, hepa vacuumed and new samples and swabs taken before clearing the area.
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4 hours ago, Wtimmins said:
Anything anyone can equip me with before I return to the school and try to figure out what is wrong despite all new components, would be very much appreciated!
Just to add to Neil’s thoughts which are great - you can download the manual from the Paragon website. Browsing it for the lag error indicates the kiln did not warm up at a minimum rate of 9 f degrees per hour and that error only occurs below 500 degrees. so it sounds like it was programmed to fire but never really began heating. You mentioned continuity, but did you test fire this?
Anyway the sentry 3.0 manual I read described the lag error on page 9 and also contained a wiring diagram for the controller near the end of the manual. You may want to print it to be sure the wiring matches. Setup programming may be necessary for this as Neil mentioned, how many thermocouples? How many are programmed?
You are correct - one of the possibilities for a lag error is one of the thermocouple leads are shorted to the shell so yes that is a possibility.. Run the test fire, I think you will find out quickly. I did not see number error references but a call to Paragon probably gets a quick answer for those. Continuity is great but testfire to be sure.
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On 5/1/2024 at 9:17 AM, HenryBurlingame said:
! I actually have been thinking about exploring slow cooling as well as putting things in saggars to get reduction effects.
Reduction only affects a handful of metals. The reality, nice to explore, fun to learn, extremely wasteful, environmentally and from an energy standpoint. Exploring other methods may be the future.
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50 minutes ago, JohnnyK said:
I think the slot is too narrow for the shaft.
You should be able to find a variety of sizes (Truck ball joints and heavy equipment a bit larger) - not sure it’s worth the pursuit though. My thought is it’s 3/4”- 1” shaft. Likely need to cut up some washer for spacing and bearing though. One that fits in a large hammer drill available also for extra stuck stuff. After reading your post though if you can get a head, I would probably cut it off also.
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Having seen this now, my inkling is extractor in a decent drill impact for the setscrew. The wheel head screams pickle fork (ball joint separator) and appropriate number of C washers to hopefully pop the head with minimal damage and hopefully no damage to the shaft. Gotta have a replacement head ready though. It’s an idea!………
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Min has a great point especially if it does not perform well. It’s hard to change the weight of the glaze that way, unless ….. it’s not stirred really well. So if you are just skimming water off the top when measuring, make sure it is mixed well and not a whole bunch of ingredients are at the bottom of the bucket.
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Most glazes thicken over time if the water is allowed to evaporate. My thought is this was mixed with a lower specific gravity at some point. You could allow this to evaporate to get to a preferred SG. It’s a commercial glaze so no way to know what is in it and if it likely will perform as expected without testing once restored to your preferred SG
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On 4/25/2024 at 11:05 AM, HenryBurlingame said:
I have been interested in pottery for a long time, and now finally have a chance to set up a small studio and spend more time doing it.
An interesting thought if you have never done any sort of pottery maybe take a course or two if possible, to see what you may like. Learning to build a gas kiln and operate it reasonably proficient - maybe a year or two. Learning and becoming proficient in all aspects of pottery - maybe a lifetime.
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It’s a wheel, at 2.2 amps you are free to use most any three wire extension cord. So 3 wire 16/3, maybe 15 ft is rated well beyond your wheel. I would change the receptacle it is plugged into to a gfi receptacle with appropriate cover from weather. You can buy a cord with the gfi built in, but they are fairly pricey. I would not use this outdoors unless protected by a GFI though. A GFI can only protect you if the cord has all three prongs and the wheel has a three prong plug.
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My experience with carbon trapping, most dependent on the firing cycle. Very fine soot during the cycle readily is trapped, sometimes uniquely because water has randomly splashed on the object which has attracted the solubles to spots on the ware. The mistake I see made most often is in the reduction firing. Generating too much soot in the firing (not good) rather than fine char usually points to poor technique.
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On 4/25/2024 at 11:05 AM, HenryBurlingame said:
So many things to think about, any help would be appreciated!
I think all thats been mentioned above are great. I would add from an expectation standpoint If you are constructing a fuel fired kiln especially for a first time, there will likely be a decent learning and testing curve. Great fun and usually very educational for those that persevere and succeed.
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42 minutes ago, Marilyn T said:
if I don't get an error code then I'll assume it is within its acceptable speed range.
I would agree. Most often when elements run out of power you will see it in a very significant deviation of the final rate, significant extension of the final segment timing ………. followed by the errors. You will know in advance before this happens with your level of observation for normal element wear.
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If I understand this, you programmed for 108/hr and actual firing it achieved 120/hr. Further you programmed 350/hr and it actually achieved 344/hr. My initial thought is it was operating at the Precision it could. In the 108/hr segment (more overshoot in the algorithm) and in the 350/hr segment maybe a combination of what it could achieve power wise and undershoot in that segment. So my initial thought is many times programs do not fire perfectly at the rate programmed. Quite often when rates are programmed that exceed the actual power available they really go a lesser rate. How well a controller matches temperature throughout the firing is dependent on several programmed characteristics in the controller. One would be relay cycle time. My experience, kiln controllers do a pretty nice job of matching the kiln characteristics so those actuals would not alarm me. It would tell me though for that loading, you don’t quite have enough power to maintain 350/hr, very close though and you have enough power to maintain 108 degrees per hour in the final segment.
The final segment to me is most important as that is where you are providing significant heatwork to match the Orton columns of maturity. Orton says this starts 200 -250 f from the desire peak temperature (in the Orton chart) The ten minute hold, Ireally can’t speak to, maybe you were trying to drive this 1/2 cone higher.
People have all kinds of schedules that work for them, often very different and much more complex than just following the instructions In the Orton chart. The big question to me is did it fire to the cone you were seeking?
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It sounds like your power source is not able to supply all elements in parallel. A 2400 watt element with 240v across it draws 10 amps. 20 of these in parallel would be 200 amps. That would be 48000 watts of heating energy. Very large home kilns are approx 12000 watts of energy. Each element right now should be 24 ohms as you have designed.
So my sense is when you connect several of these in parallel whatever power supply you are using has a severe voltage drop and they do not heat up as expected. I would combine these in series parallel to get down to 12000 watts which means an overall resistance of about 5 ohms. Unless you have built the biggest kiln ever, 48000 watts is too much. At 12000 watts your power supply will need to be capable of supplying 240 v @ about 48 amps without significant voltage drop.
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13 minutes ago, tman123 said:
I have heard of people firing on drywall, is this ok for the elements? What about just building on top of a kiln shelf?
Don’t fire on drywall it will smolder and burn once calcined. Used to be type X 5/8” - approx. 60 minutes, 120 minutes to sustain a flame. I like the shelf idea and unless once firing, you can grog / silica the shelf after bisque. Many of our large format sculptors would build on a very straight shelf on top of a four wheeled cart.
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On 4/22/2024 at 10:14 AM, Hendrixl114 said:
do you have any suggestions for a clear glaze that might work better over underglaze that I can buy? I have seen several commercial glazes (laguna I think) that I was thinking of trying. Also, does it matter whether I am using porcelain or stoneware? Is this just a glaze issue or a glaze + clay issue?
I do not have a preferred store purchased overglaze. I spent a whole summer trying to resolve this for our cone 6 glazes so our artists could paint freely with most underglazes. The solution was to modify a clear with a bit more boron to more completely melt. If this is your issue then testing other commercial. over glazes as well as lighter coats of underglaze are probably your best bet.
I have never noticed a difference between clays but only anecdotally tested on the variety of studio clays used at the time. Color, thickness applied and even underglaze supplier had the greatest effect - all reasonably resolved with a slightly lower melting temperature of the modified clear. Not all under glazes will go to cone 10 as well with significant color change often being the effect of higher temperature. All our artists, especially sculpture test their underglazed for color. It was not uncommon for a sculpture artist to say, I need to stop at cone 2 - no higher as the perfect color of a full sized human bust that took them a month to make might change from what they wanted. A bit tedious, but an example of all tested in advance.
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In the UK the declared mains voltage has been 230v single phase I believe. North America uses 240v but split between 2 phases ends up at two 120v circuits to neutral. I think it would be odd to have 120v available without your very own step down transformer. Check before buying for sure to be safe. Check a light bulb or two - ought to be rated at 230v in the UK.
Bisque firing quit at 1353 after 6 hours
in Clay and Glaze Chemistry
Posted · Edited by Bill Kielb
Ya probably already know this but worth mentioning I think. Breakers fail because they are old but also because they overheat. Here in the US the breakers you buy should not exceed 80% of the rating stamped on the breaker. For kilns which are considered continuous loads by code, per code they require a breaker at least 125% of the kiln full load and not more than 150%.
For a kiln that draws 40 amps, minimum breaker size is 50 amps (40X 1.25), maximum breaker size is 60 amps (40X1.5). I mention because electricians often get this wrong. The rule is there to prevent the breaker from overheating and failing prematurely. Often this is not common knowledge so I think worth passing along since you just experienced a worn out breaker on this kiln.